The biological authentication technology of authenticating a person using an image of a finger is known as a technique of collating a pattern of epidermis such as a fingerprint, and a pattern of a blood vessel with pre-registered information.
One example of such a biological authentication technology is described in Patent literature 1.
FIG. 10 is a block diagram of the invention of the Patent literature 1.
In the invention of the Patent literature 1, when personal identification utilizing a blood vessel pattern of the finger is performed, the finger, being a target of authentication, is placed between infrared light sources 310 and 320 and an infrared-transparent filter 330. When a driving circuit 360 is driven by a microcomputer 370 to turn on the infrared light source 310, the blood vessel pattern is imaged onto an image sensor 350 via a lens 340 because infrared light is absorbed by hemoglobin of the blood. Additionally, the infrared-transparent filter 330 has a feature of blocking visual light that becomes noise at the moment of obtaining the blood vessel pattern, and allowing only the infrared light in which the blood vessel pattern is included to be transmitted. On the other hand, when personal identification utilizing a fingerprint pattern is performed, the finger, being a target of authentication, is placed at a position identical to the position in which the personal identification utilizing the blood vessel pattern of the finger is performed. When the infrared light source 310 is kept being turned off, the surface of the finger is imaged onto the image sensor 350 via the lens 340. The blood vessel pattern or the fingerprint pattern imaged by the image sensor 350, which is subjected to a photoelectric conversion and is converted into an electric signal, is inputted into the microcomputer 370. Additionally, the infrared light source 320 is turned on in order to obtain brightness sufficient for obtaining the fingerprint pattern.
In such a manner, the invention of the Patent literature 1 is the personal authentication device of separately imaging the blood vessel and the fingerprint with a single imaging means by switching the light source for emitting light.
Further, the biological image input device including an imaging unit that makes infrared light incident into the inside of the finger and takes the fingerprint image and the blood vessel image by use of its scattered light is described in Patent literature 2. The above biological image input device, which includes a window material in which a fiber plate and a transparent plate of which thickness is thicker than that of the fiber plate are arranged in parallel on a light incident side of the imaging unit, is configured to image the fingerprint through the fiber plate side of the window material and to image the blood vessel through the transparent plate side of the window material therewith in such a manner that the fingerprint of a fingertip part is contacted with the fiber plate side of the window material.